In the past, the main concern in odontology was to diagnose and treat established lesions derived from caries. There was no known means of controlling the disease and the only treatment possible was the removal of the caried tissue to impede the progress of the lesion, restoring that dental element. Today, with the increase of knowledge, this concept has changed and odontology has turned to promoting health through an early diagnostic followed by counseling to enable the patient to control the disease himself. In this manner, epidemiological studies have shown that there has been a reduction of caries and gingival disease percentages.
Bacterial plaque is considered one of the aetiological factors of dental caries and periodontal disease which places therefore great importance on the application of preventive measures as a means of keeping buccal structures healthy.
Dental plaque is a well-organised structure that forms over the surface of teeth, restoration and protheses and consists, mainly, of an organic matrix derived from saliva and from bacteria existing in the buccal cavity.
The mechanism for forming plaque occurs with bacteria of the most diverse forms present in saliva (coccus, bacillus, coccobacillus, etc.) that begin depositing until totally covering the dental surface. The thickness of the bacterial plaque is related to the ingestion of saccharose and with buccal hygiene, and becomes a factor that causes demineralisation of the enamel that results in dental caries and periodontal irritation leading to infectious periodontal processes. The effective removal of these deposits becomes essential for the control of diseases associated to plaque.
To this end, various recourses must be used to motivate the patient to practice buccal hygiene. Experience has shown that the majority of patients are not sufficiently motivated to practice good buccal hygiene merely by being informed that plaque means that a bacteria colony is growing around their teeth and that this plaque causes caries and diseases of the gums, therefore requiring frequent removal. However, the global concept of what plaque means and what it is capable of doing to tissues may become more striking to the patient through visualisation, in the sense that each patient will be able to observe the plaque in situ.
The resources used presently to motivate patients range from direct instruction (posters, graphs and macro-models) (Dotto, C. A. and Sendik, W. R. Atlas de higienizacao bucal. Sao Paulo: Panamed, 88p., 1982. In: LASCALLA, N. T. Prevenão na Clínica Odontológica. Prevenão e motivaão na Clínica Odontológica. P 59–80) to indirect instruction or self-instruction (explanatory pamphlets, films, information about diet, plaque and buccal hygiene) (COUTO, J. L., COUTO, R. S. Programa de motivaão do paciente. RGO (Porto Alegre), v. 40, n. 6. P. 433–438, November/December, 1992).
Self-care through buccal hygiene (brushing and use of dental floss) is efficient in the control of bacterial plaque, however it is necessary to motivate the patient to perform the appropriate hygiene capable of promoting efficient mechanical disruption to avoid buccal diseases.
Thus, the use of compositions for evidencing plaque has been recommended by professionals with the intent of increasing the detection and the effective removal of plaque. These disclosing solutions contain colouring agents or pigments that are absorbed by the plaque and render it visible so as to be eliminated. The majority of the disclosing compositions are based on iodine or organic colorants.
Organic colorants have been almost universally employed for use in disclosing compositions due to their high degree of efficiency. However, in the majority of cases these colorants possess very unpleasant flavours that are not effectively masked by any of the known flavoring agents or sweeteners.
Organic disclosing agents such as, amongst others, erythrosin (FDC Red #3) are described in patents U.S. Pat. No. 3,309,274, U.S. Pat. No. 3,624,219, U.S. Pat. No. 3,997,658, U.S. Pat. No. 4,302,439, U.S. Pat. No. 4,992,256 and U.S. Pat. No. 4,459,277. The patent U.S. Pat. No. 3,624,219 mentions that erythrosin is the agent of preference compared to others such as Amaranth and Brilliant Blue, as these latter are excessively soluble in water and do not penetrate or persist in the mouth in the proportions desired for the purposes of disclosing plaque. The patent U.S. Pat. No. 3,309,274 uses the synthetic fluorescent colorants FDC Colors Red #3, Green #8, Red #19, Red #22, Red #28, Yellow #7 and Yellow #8 which are invisible to the human eye in normal daylight or artificial light and only become visible through the use of light on the appropriate wavelength.
Erythrosin was recommended as a colorant rather than fuchsin, a solution of thymerosal (Merthiolate®) and neutral red for use in teaching buccal hygiene and in the prevention of dental diseases. The solution of thymerosal is considered a weak disclosing agent, with an unpleasant taste that takes time to leave the mouth, as well as containing a substance that is considered cancerous. Fuchsin is also suspected of being cancerous. (ARNIM, S. S.; “The use of disclosing agents for measuring tooth cleanliness”. Journal of Periodontology. 34, 227–245. 1963).
However, erythrosin also presents disadvantages inasmuch as it possesses a very high retention time with an undesirable colouring of the patient's mouth, a weak contrast between the gingival tissue and the coloured plaque as well as an unpleasant taste.
In this sense, natural colorants have been suggested as alternatives to the use of synthetic organic colorants for use in the practice of buccal hygiene motivation. According to Guimaraes (GUIMARÃES, I. S. S., Corantes naturais: os sucedâneos dos artificiais. In: Revista Brasileira de Corantes Naturais. Sociedade Brasileira de Corantes Naturais. Embrapa—CPATU, vol 2, n.1, p.98–110, 1996), artificial colorants have disadvantages which natural colorants do not present. Some artificial colorants provoke diseases of the thyroid, lesions of the liver, hyperacidity and allergies such as, for example, asthma, rhinitis and rashes.
Examples of natural colorants used to disclose bacterial plaque may be encountered in patents U.S. Pat. No. 4,431,628 and U.S. Pat. No. 4,517,172. The patent U.S. Pat. No. 4,431,628 refers to a method for indicating the presence of bacterial plaque, comprising an efficient quantity of natural colorant extracted from sugar beet. This method employs a disclosing composition that may be provided in the form of tablets, solutions, gels or aerosols. The roots of the sugar beet contain red and yellow pigments that belong to the betalayin class—quaternary ammonia amino acids—which are divided into betacyanins (red) and betaxanthins (yellow).
Patent U.S. Pat. No. 4,517,172 describes a method for the visualisation of plaque, in such a manner that the plaque is visible to the naked eye under ultraviolet light. The method employs a salt of sanguinarine precipitated from extracts of plants selected from the group consisting of Sanguinaria canadensis, Macleaya cordata, Corydalis sevctvozii, C. ledebouni, Chelidonium majus and mixtures of these. It presents the inconvenience of requiring ultraviolet light to enable visualisation, which makes frequent use by patients in their homes difficult.
The comments above demonstrate the importance of developing formulations containing plaque evidencing agents of natural origin both efficient and of selective efficiency.